FCC-ee Interaction Region design CERN has recently launched the ambitious project of the Future Circular Collider. The same 100 km tunnel will host a hadron-hadron collider with pp collisions at 100 TeV center-of-mass energy (FCC-hh) and e+e- collisions up to 350 GeV center-of-mass energy (FCC-ee). The two colliders should be built in the same tunnel (as was for LEP and LHC). This challenging design study involves a worldwide collaboration with great accelerator physics experts on all the different fields. INFN participates to the FCC-ee and FCC-hh study (MoU), in particular: There is a WG for Machine Detector Interface (MDI) in CSN1 of INFN, within RD_FA. INFN is part of EuroCirCol, the European design study for some key topics of FCC-hh funded by EU under Horizon 2020 (4 years project, started June 2015) Goal of the study: CDR ready before the next European strategy, by end 2018. The design of the Interaction Region for FCC-ee is very challenging and is a fundamental step for the feasibility of the collider. The work for the PhD thesis will focus on the Interaction Region design within the Machine Detector Interface group, on particular aspects of the design, namely The activity will be to develop particle tracking studies for the main beam loss effects, relevant for the interaction regions design. Possibility of Benchmark tools with existing colliders, like the LHC and SuperKEKB.

Useful Links FCC page at CERN: https://fcc.web.cern.ch/ INDICO page with all FCC meetings: http://indico.cern.ch/category/5153/ FCC-ee: FCC-ee Optics meetings: http://indico.cern.ch/category/6528/ FCC-ee MDI meetings: http://indico.cern.ch/category/5665/ FCC-hh: FCC-hh General Design meetings: http://indico.cern.ch/category/5623/ FCC-hh beam delivery system meetings: http://indico.cern.ch/category/5902/ FCC-hh MDI meetings: http://indico.cern.ch/category/5901/ EuroCirCol: http://indico.cern.ch/category/6457/

FCC-ee IR baseline Layout beam Beam energy GeV 175 bx* / by* m /mm 1/2 ex / ey nm/pm 1.3/2.5 sx / sy mm/nm 36/71 L* m 2.2 full crossing angle mrad 30 Beam current mA 6.632 Npart/bunch # 1.7x1011 bunches 81 This layout is the starting point for: detailed design of masks and shielding tracking of off-momentum particles Beamstrahlung, radiative Bhabha simulation beam pipe geometry and material luminosity monitor

Background Studies in the FCC-ee Interaction Region Contribution to the particle tracking simulation for evaluation of beam losses, relevant for the interaction regions design. Particle tracking simulation studies for various effects that induce beam losses in FCC Interaction Region and all over the ring , such as: Radiative Bhabha (Integration with BBBREM) Beamstrahlung (Integration with GUINEAPIG) beam-gas scattering -> existing software tools / development and upgrade Also : MAD-X for the magnetic lattice description ROOT GEANT4 for interaction in materials Investigate luminosity-driven losses and its impact on beam intensity lifetime (for FCC-ee). Use developed software to design shielding and absorbers, optimizing beam pipe dimensions. Benchmark tools with existing colliders, like the LHC for the FCC-hh studies and SuperKEKB

Synchrotron Radiation from the last bend before the IP Example: MDISIM[*] Zoom on the last 200m aperture shown as circular r=20 mm central BP, quads r=50mm bends Last bend closer than in LEP2 ( 250 m / 100 m )^2 = 6.25 more solid angle less space for collimators, part for far bend - SR fans directed towards IP  From last bend LEP2 FCCee_t_74_11 Eb 100 GeV 175 GeV Ecr 72 keV 100 KeV bunchXfreq 45 kHz 180 kHz γ’s / crossing 3.E+11 4.E+11 γ’s Σ energy / crossing 7.E6 GeV 1.2E7 GeV [*] : H.Burkhardt and M. Boscolo, Tools for Flexible Optimisation of IR Designs with Application to FCC, IPAC 2015, tupty031

FCC-ee baseline parameters Z WW ZH ttbar energy/beam [GeV] 45.6 80 120 175 bunches/beam 30180 91500 5260 780 81 bunch spacing [ns] 7.5 2.5 50 400 4000 bunch population [1011] 1.0 0.33 0.6 0.8 1.7 beam current [mA] 1450 152 30 6.6 Horizontal emittance [nm] 0.2 0.09 0.26 0.61 1.3 Vertical emittance [pm] 1 1.2 luminosity/IP x 1034cm-2s-1 210 90 19 5.1 bx* [m] / by* [mm] 0.5/1 1/2 energy loss/turn [GeV] 0.03 1.67 7.55 SR power /beam [MW] RF voltage [GV] 0.4 3.0 10 Energy acceptance RF [%] 7.2 4.7 5.5 7.0 6.7 Luminosity lifetime [min] 94 185 67 57